Reamer With Stabilizers For Use In A Wellbore

ABSTRACT

A reamer bit for use in earth boring operations comprising a body, cutter mounts having rolling cutters on the bit body, and stabilizers pads on the body placed between adjacent cutter mounts. The reamer may further include a pilot bit on a drill pipe extending downward from the reamer body. The reamer bit outer periphery with its stabilizers and bit body has a radial profile approximating a circle thereby reducing dynamic perturbations during drilling operations.

RELATED APPLICATIONS

This application claims priority to and the benefit of co-pending U.S.Provisional Application Ser. No. 61/016,209, filed Dec. 21, 2007, thefull disclosure of which is hereby incorporated by reference herein.

BACKGROUND

1. Field of Invention

This disclosure relates to earth boring reamer bits, and particularly toreamer bits having stabilizers disposed on the bit body.

2. Description of Prior Art

Drill bits used in drilling of subterranean well bores typicallycomprise drag bits and roller cone bits. Roller cone bits typicallycomprise a body having legs extending downward and a head bearingextending from the leg towards the axis of the bit body.Frusto-conically shaped roller cones are rotatably mounted on each ofthese journals and are included with cutting teeth on the outer surfaceof these cones. As the bit rotates, the cones rotate to cause thecutting elements to disintegrate the earth formation.

In some situations a pilot reamer drilling system is employed where twoor more bits are combined on a single drill string at different verticalpositions. The lower bit of the pilot reamer drilling system, which iscommonly referred to as a pilot bit, creates a pilot hole. The upperbit, which follows the lower bit in the drilling process, enlarges thehole diameter over that created by the pilot bit. The bit enlarging thehole diameter is referred to as a reamer bit. Typically the pilot bitcomprises a conventional earth boring bit, i.e. either a roller cone bitor a drag bit. The reamer bit usually employs roller cone bits ascutting members modified for attachment to the reamer bit body. Pilotreamer drilling systems are used for drilling large diameter wellboresor surface holes which require enhanced stabilization.

SUMMARY OF INVENTION

The disclosure herein includes a reamer bit for downhole earth boringoperations comprising, a reamer body having an axis, rolling cuttersmounted on the body, and stabilizers disposed between adjacent cutters.Pockets may be provided on the body outer diameter formed to receive thestabilizers and cutter mounts therein. A pilot bit is affixed to thedrill shaft extending from the body's lower end. The pilot bit can be aroller cone bit or a drag bit. An updrill surface may be included formedon the upper portion of the cutter mounts and the stabilizer pads. Thecombined radial profile of the bit legs and the stabilizer pads canapproximate a circular shape.

In an alternative embodiment, the present disclosure includes a pilotreamer apparatus for earth boring use comprising a reamer body having anupper end and a lower end, an axis extending through the upper and lowerends, an outer periphery circumscribing the axis, and pockets formed inthe outer periphery, a drill string attachment on the body upper end, adrill pipe segment on the body lower end, a pilot bit affixed to thedrill pipe terminal end, cutter mounts on the body outer peripheryextending downwardly, rolling cutters rotatingly affixed to the mounts,and stabilizer pads affixed to the reamer body outer periphery disposedbetween adjacent bit legs.

BRIEF DESCRIPTION OF DRAWINGS

Some of the features and benefits of the present invention having beenstated, others will become apparent as the description proceeds whentaken in conjunction with the accompanying drawings, in which:

FIG. 1 is a side view of a reamer bit body with rolling cutters andstabilizer pads.

FIG. 2 is a perspective view of a reamer bit with attached pilot bit.

FIG. 3 is an upward looking view of a reamer bit in accordance with thepresent disclosure having stabilizers.

While the invention will be described in connection with the preferredembodiments, it will be understood that it is not intended to limit theinvention to that embodiment. On the contrary, it is intended to coverall alternatives, modifications, and equivalents, as may be includedwithin the spirit and scope of the invention as defined by the appendedclaims.

DETAILED DESCRIPTION OF INVENTION

The present invention will now be described more fully hereinafter withreference to the accompanying drawings in which embodiments of theinvention are shown. This invention may, however, be embodied in manydifferent forms and should not be construed as limited to theillustrated embodiments set forth herein; rather, these embodiments areprovided so that this disclosure will be thorough and complete, and willfully convey the scope of the invention to those skilled in the art.Like numbers refer to like elements throughout.

It is to be understood that the invention is not limited to the exactdetails of construction, operation, exact materials, or embodimentsshown and described, as modifications and equivalents will be apparentto one skilled in the art. In the drawings and specification, there havebeen disclosed illustrative embodiments of the invention and, althoughspecific terms are employed, they are used in a generic and descriptivesense only and not for the purpose of limitation. Accordingly, theinvention is therefore to be limited only by the scope of the appendedclaims.

FIG. 1 provides in a side view an example of a reamer 20 comprising agenerally cylindrical body 22 having cutter mounts 24 and stabilizerpads 28 affixed on its outer lateral periphery. The stabilizer pads 28are disposed between adjacently located cutter mounts 24. In theembodiment shown, the cutter mounts 24 and the stabilizer pads 28 areelongate members wherein their lengthwise axes are substantially alignedwith the axis A of the bit body 22. Each cutter mount 24 comprises abearing shaft (not shown) extending from the outer end of the mount 24in a generally downward direction in towards the axis A. Cutters 26 arerotatably mounted on each shaft and have rows of inserts or teeth 27formed in a generally circumferential arrangement on the cutters outersurface. The inserts 27 also referred to as cutting elements may besecured to the cutter shell in apertures of selected dimensions,integrally formed, such as by machining (teeth), or later attached afterforming the cutter 26 and affixed by welding and/or brazing.

The reamer 20 further includes a connector 34 on its upper end, whereinthe connector is generally concentrically placed around the axis A ofthe cylindrical body 22. The connector 34 includes threads (not shown)for connection to an associated drill string. A shaft 36 is shown at thebottom end of cylindrical body 22 and extends downward for attachment ofa pilot drill bit. Pockets 30 may be formed on the lateral periphery ofthe body 22 configured to receive cutter mounts 24 and stabilizer pads28. The bit legs and stabilizer pads 28 may be welded or brazed to thebody 22. Furthermore, hard facing 32 may be included on the outersurface of the stabilizer pads 28. Additionally, the upper portion ofthe stabilizer pads 28 and cutter mounts 24 may be included with ridgesinserts, or other raised elements for providing an updrilling functionwhen drawing the reamer 20 upward within the well bore.

FIG. 2 provides a perspective view of the reamer 20 combined with theshaft 36 and a pilot bit 38 fixed to the lower terminal end of the shaft36 thereby forming a pilot reamer assembly 18. The assembly 18 may beattachable to the lower end of a drill string (not shown) and attachedthereto by the connector 34. While the pilot bit 38 is illustrated as adrag bit, it may also comprise a roller cone bit. The pilot reamersystem 18 of FIG. 2 may be used to drill large diameter boreholes inwhich conventional drill bits are less stable due to the radial distancebetween adjacent cutters.

FIG. 3 is an upward-looking view of a bottom of a reamer 20 embodiment.In this view the stabilizer pads 28 extend downward between adjacentlypositioned cutters 26 of corresponding mounts 24. The stabilizer pads 28enhance reamer 20 outer circumference surface continuity by providingadditional borehole diameter contact points on the reamer outer surface.Enhancing the reamer 20 outer circumference surface continuity alignsthe bit in the wellbore and limits the lateral displacements anddistributes the side loads more evenly when a cutter 26 tangentiallystrikes the wellbore wall. Thus better alignment promotes rotation aboutthe center of the reamer and prevents dynamic dysfunctions such as bitwhirl.

To help maintain a continuity of surface, the stabilizer pads in oneembodiment may have an outer profile or curvature substantially the sameas the outer profile of the cutter mounts. The result of this can beseen in FIGS. 2 and 3 wherein the reamer 20 has a generally circularconfiguration due to the presence of the stabilizers 28. The circularconfiguration is also attributed to the pad outer surface having largediameter curvature and the stabilizer pads 28 having an outer radialprofile similar to the cutter mounts 24 outer radial profile. Thissimilarity in outer radial approximates a full circle, thus limitingopen spaces that may produce lateral displacements and high side forcesduring reaming operations.

The stabilizer pads 28 can have any shape or configuration suitable forsmoothing bit operations and total contact area. This includes anelongate member where the elongate axis is parallel to the body axis,perpendicular to the body axis, or oblique to the body axis. Moreover,the reamer 20 profile having stabilizer pads 28 is not limited to asubstantially circular shape, but can be any shape, such as one havingmultiple sides where a side is defined as the area between each adjacentstabilizer pad 28 and cutter mount 24.

1. A reamer bit for downhole earth boring operations comprising: areamer body having an axis; cutter mounts attached to the body; a cutterrotatably attached to each mount; and stabilizer pads disposed on thebody between adjacent cutter mounts.
 2. The reamer bit according toclaim 1, wherein the stabilizer pads and cutter mounts are disposedsubstantially parallel to the body axis.
 3. The reamer bit according toclaim 1, further comprising pockets provided on the body outer diameterformed to receive the stabilizer pads therein.
 4. The reamer bitaccording to claim 1, further comprising a drill shaft extending fromthe body lower end and a pilot bit affixed to the drill shaft terminalend.
 5. The reamer bit according to claim 4, wherein the pilot bitcomprises a bit selected from the list consisting of a roller cone bitand a drag bit.
 6. The reamer bit according to claim 1, furthercomprising an updrill surface formed on the upper portion of the bitlegs and the stabilizers.
 7. The reamer bit according to claim 1,further comprising hardfacing on the outer surface of the stabilizerpad.
 8. The reamer bit according to claim 1, wherein the stabilizer padshave an outer radial profile that substantially tracks the outer radialprofile of the cutter mounts.
 9. The reamer bit according to claim 1,wherein the combined radial profile of the cutter mounts and thestabilizer pad approximates a circular shape.
 10. A pilot reamerapparatus for earth boring use comprising: a reamer body having an upperend and a lower end, an axis extending through the upper and lower ends,an outer periphery circumscribing the axis, and pockets formed in theouter periphery; a drill string attachment on the body upper end; adrill pipe segment on the body lower end; a pilot bit affixed to thedrill pipe terminal end; cutter mounts on the body outer periphery;cutters rotatingly affixed to the cutter mounts; and stabilizer padsaffixed to the reamer body outer periphery disposed between adjacentcutter mounts.
 11. The pilot reamer apparatus of claim 10 furthercomprising a drill string affixed to the drill string attachment. 12.The pilot reamer apparatus of claim 10 wherein the stabilizer pads havean outer profile substantially the same as the bit leg outer profilewith relation to the bit body axis.
 13. The pilot reamer apparatus ofclaim 10 further comprising hardfacing.
 14. The pilot reamer apparatusof claim 10, wherein the pilot bit comprises a bit selected from thelist consisting of a roller cone bit and a drag bit.
 15. The pilotreamer apparatus of claim 10 comprising four cutter mounts disposed onthe outer periphery of the bit body and four stabilizer pads eachdisposed between adjacent bit legs, wherein the stabilizer pads are insubstantial parallel alignment with the bit legs.
 16. The pilot reamerapparatus of claim 10, wherein the combined outer radial surfaces of thecutter mounts and the bit bodies approximate a circle.
 17. The pilotreamer apparatus of claim 10 further comprising an updrill cuttingfeature formed on upper portions of the stabilizer pads and the cuttermounts.